Traditional search engines operate as follows. A user inputs a search query into the search engine. The search query may include a number of search terms, perhaps issued in conjunction with Boolean search operators. In response to the search query, the search engine returns a ranked list of document titles, along with their uniform resource locators (URLs) and snippets indicative of each document's content or relation to the search query. The document titles are typically hyperlinked to the source documents.
Information about the hyperlinked documents is typically presented in order of descending relevance and, in more recent search engines, document merit, where document merit is calculated independently of the search query that resulted in identification of the documents. It is up to a user to scan the search results to determine which documents are worth retrieving entirely in order to obtain desired information.
Some search engines, referred to herein as “answer engines”, return short answers to queries that express a question (e.g., “What is the capital of Sweden?”) or are implicitly related to such a question (“capital of Sweden”) instead of, or in addition to, returning a ranked list of documents. This short-answer functionality may use special authoritative sources, such as encyclopedias or almanacs, from which the answers are derived.